Method of processing lubricating



Patented July 17, 1951 'OIL BY SOLVENT-EXTRACTION AND TREATING WITH APHOSPHORUS SUL- FIDE AND CLAY AND THE RESULTING PRODUCTS John D.Bartleson, East Cleveland, Ohio, assignor to The Standard Oil Company,Cleveland, Ohio, a corporationo'f Ohio N Drawing. Application May 29,1948, Serial No. 30,205

8 Claims. 1

This invention relates to processes or improv'* ing hydrocarbon baselubricants, and more par ti'cula'rly to subjecting hydrocarbon lubricantstocks to a conventional solvent refining treatmerit, and then to thetreatment of the solvent refined hydrocarbon with a small amount of aphosphorus sulfide. A clay treatment before and after the sulfiderefining is included and the refined lubricants have improvedproperties, especially as to corrosion, lacquer, sludge, viscosityincrease, and the like characteristics. It also relates to the resultingimproved lubricants.

Many of the commercially used lubricants are based upon-hydrocarbonstock, whch may be s nthetically preparedor which may be derived fromnatural sources, "such as petroleum. For many purposes so-calledadditives must be included with the hydrocarbon in order to provide alubricant having particularly desirable characteristics. This isespecially so in the case of solvent refined oils which are known to becorrosive. Generally, the addition of these additives is associated witha higher cost of the finished lubricant. The preparation of a'finishedlubricant directly from hydrocarbon stock by a chemicalfinishin'gorrefining process at a commercially interesting cost has beenan especially hard problem in this art.

In accordance with the invention, it hasbeen found that hydrocarbonlubricating oil stock 'may be extracted with an aromatic removingsolvent such as sulfur dioxide, furfural, phenol or the like, in the"known manner, and the resulting solvent-refined raffinate is treatedwith a small amount of a phosphorus sulfide. A clay treatment after orbefore and after the sulfide refining is included. The resulting refinedoil is 'an improved lubricant; i. e., a chemically finished or refinedlubricant. Such lubricants are suitable for use under variousconditions, including high temperatures or high pressures or both; as,forinstanoe, use in an internal combustionen gine'operating at hightemperatures and inwh ich the lubricant is in close contact withmetallic surfaces, metalcompounds and high temperature ases. pressurelubricants, e. g., in oils and greases-containing' them. 1

Treatment ofthe hydrocarbon oil with the solvent maybe carriedonintheconventional manner, e. g., in accordance with modern methods ofrefining lubricating oil. In general, the solvent tends to removearomatic, unsaturated, and-low viscosity index constitutents and these'are separated from the oil. The step is "vvell known in the art ofsolvent refining or solvent extraction They are also suitable for use inextreme conducted with direct admixture, or, if desired, by theiradmixture in the presence of a diluent which may besubsequently'removed. Generally, a diluent is not necessary. The sulfidetreating step is usually complete in about 10 hours or less time,generally 1 to 2 hours. The treating time is a function of thetemperature, the amount of sulfide that is to react, the subdivision ofthe reactants, the efiiciency of mixing the reactants, and the like.

The solvent refined hydrocarbon lubricant stock is reacted with thephosphorus pentasulfide in a ratio of from about 0.1 to about 0. byweight, based on the weight of the hydrocarbon stock, desirably aboutO.25.to about 0.6 At least about 0.1% of the sulfide should be used toachieve the results desired on a commercial scale, although smallamounts show improvement.

The treatment of the hydrocarbon with the phosphorus sulfide may becarried out in the presence or absence of air, or in an atmosphere ofinert or non-deleterious gas, such as nitrogen or Has. It may also becarried out under pressure, e. g., pressure of the inert gas or thatgenerated when the reaction is carried out in a closed vessel.

The sulfide treating temperature varies with the hydrocarbon lubricatingstock. Generally, the temperature should be at least 275 F., but shouldbe below the temperature at which the reaction product would bedecomposed. A temperature in the range of about 300 to about450 F. ispreferred in many cases. The treated oil mass is preferably centrifugedor filtered to remove any by-products, sludge, orotherby-productmaterial. If a volatile diluent i used, it may be removedby evaporation.

Theclay treatment, which is the third essential step of the process, iscarried out after the sulfide treatment and is accomplished by treatingthe oil with l to 25 pounds of clay per barrel of oil. The'temperatureis usually in the range of to 350 F. The clay is separated byfiltration. The treatment may be before as well as after the sulfiderefining.

The hydrocarbon lubricant stock to which the process is applied may be araw oil, 1. e., a fiuid hydrocarbon having a viscosity at 100 F. of 10to 500 centistokes, such as that used as the base for the S. 'A. E. 10'to 50 oils. It may be obtained as a distillate or from syntheticmaterial, such as petroleum, {and oils'produc'ed by cracking,polymerization; hydrogenation, and the likemethods.

In'ordertoillustratean'd point out some of the advantages of theinventionbut in no sense a ll'lfl ation thereof, the'followingspccificembodimerits-are included.

--In *th'e iollowing' Examples 1 to 6 #300 Red Oil (a conventionalMid-Continent lubricating oil base stock, of 20-30 S. A. E. viscosity)is used as the hydrocarbon oil stock. The raw oil is solvent refinedwith furfural in a conventional manner, using 50% to 1000% of solventbased on the oil, and the extract and solvent are separated. The solventrefined hydrocarbon oil is then mixed with the kind and amount ofphosphorus sulfide indicated in the following table, agitated for 1 hourat 300 F., at atmospheric pressure. A good yield is obtained, based onthe hydrocarbon lubricating oil, and no sludge is formed in thephosphorus sulfide treating step. However, it is preferred to filter thefinal reaction product. In some of the examples, the clay treatment isused before (column 2), as well as after (last column) the phosphorussulfide treatment, using the amounts ofclay as indicated in thefollowing table. For comparison, samples A, B and C are included. Thereaction product is identified hereinafter by The Sohio corrosion testwas used in evaluating lubricants made in accordance with the invention.This test is described in a co-pending application of E. C. Hughes, J.D. Bartleson, M. L. Sunday and M. M. Fink, which also correlates theresults of the laboratory tests with a Chevrolet engine test.

Essentially the laboratory test equipment consists of a verticalthermostatically heated glass test tube (45 mm. outside diameter and 42cm. long), into which is placed the corrosion test unit. An air inlet isprovided for admitting air into the lower end of the corrosion unit insuch a way that in rising the air will cause the oil and suspendedmaterial therein to circulate into the corrosion unit. The tube isfilled with an amount of the oil to be tested which is at leastsufficient to submerge the metals being tested.

The corrosion test unit essentially consists in a circular relativelyfine grained copper-lead test piece of 0. D., which has a 4" diameterhole in its center (i. e., shaped like an ordinary washer). The testpiece has an exposed copperlead surface of 3.00 sq. cm. Of this surfacearea, 1.85 sq. cm. acts as a loaded bearing, and is contacted by a partof the cylindrical surface of a hardened steel drill rod (14" diameterand it" long, and of 51-57 Rockwell hardness).

The drill rod is held in a special holder, and the holder is rotated sothat the surface of the drill rod which contacts the bearing sweeps thebearing surface (the drill rod is not rotated on its own axis and thesurface of the drill rod which contacts the bearing is not changed).

The corrosion test unit means for holding the bearing and the drill rodis a steel tubing (15" long and 13%" O. D.) which is attached to asupport. A steel cup (1" long, 1 O. D. by 1%" I. D.) is threaded intothe steel tube, at the lower end. The cup has a diameter hole in thebottom for admitting the oil into the corrosion chamber. The copper-leadtest piece fits snugly into the steel cup and the hole in the test piecefits over the hole in the steel cup. A section of steel rod 0% indiameter and 19" long) serves as a shaft and is positioned by 2 bearingswhich are fixedly set in the outer steel tubing, one near the top and.one near the lower (threaded) end thereof. Several holes are drilledjust above and just below the lower bearing. The holes above the bearingfacilitate cleaning the apparatus. while the holes below the bearingenable the circulation of oil through the corrosion chamber. The drillrod holder is connected to the shaft by a self-aligning yoke and pincoupling. This assures instantaneous and continuous alignmentof thedrill rod bearing member against the bearing surface at all times. Apulley is fitted to the top of the steel shaft and the shaft isconnected therethrough to a power source. The shaft is rotated at about6'75 R. P. M. and the weight of the shaft and attached members is about600 grams, which is the gravitational force which represents the thruston the bearing. The air lift from the air inlet pumps the oil throughthe chamber containing the test piece and out: through the holes in thesteel tubing.

The ratios of surface active metals to the-volume of oil in an internalcombustion test engine: are nearly quantitatively duplicated in thetestequipment. The temperature used is approxi-- mately that of thebearing surface. The rate of air flow per volume of oil is adjusted tothe same* as the average for a test engine in operation. Of-I thecatalytic effects, those due to soluble iron are: the most important.They are empirically duplicated by the addition of a soluble iron salt..Those dueto lead-bromide are duplicated by its; addi io The test wascorrelated with the L-4 Chevrolet. test, and a slightly modified versionthereof. Themodified test comprised reducing the oil additions: from the4 quarts in the usual procedure to 2. quarts, by reducing the usual 1pint oil additions which are made at 4 hour intervals to pint ad-'ditions. This modification increases the severity. of the test in itscorrosion and. detergency components, particularly in the case of borderline: oils.

For each test, the glass parts are cleaned by, the usual chromic acidmethod, rinsed and dried. The metal parts are washed with chloroformand; carbon disulfide and polished with No. 925 emery cloth or steelwool. A new copper-lead test piece: is used for every test. The testpiece ispolished before use, on a, surface grinder to give it a; smoothfinish. The test piece is weighed before: and after the test on. ananalytical balance to evaluate the corrosion. After placing the oil and.

Table A Temperature325 F.

Oil sample-107 cc.

Air flow rate70 liters/hour- Time-10 hours CatalystsSteel; copper-leadbearing: 3 sq. cm. area of which 1.85 sq. cm. is a. bearing surface;

ferric 2-ethyl hexoate: 0.05% as F8203 in C. P. benzene; lead bromide:0.1% as precipitated powder. Bearing assembly:

Load grams..- 600 Speed R. P. M. 675

By extending the laboratory test to 20 hours, it wasfound thatcorrelation with the Chevrolet 72-hour test could be obtained.

At the close of the test period, the extent of corrosion is determinedby reweighing the corrosion test piece and determining the change inweight due to the test. An accurate evaluation of the lacqueringproperties of an oil is obtained by a visual rating system which isapplied to the outer surface of the corrosion unit steel tube and metalcup in much the same way that the piston skirt, cylinder Wall, etc, ofan engine are rated for varnishes. The sludge rating of the engine issimulated by a visual rating of the insoluble materials and used oilwhich are coated on the glass test tube at the conclusion of the test.For both sludge and varnish rating a scale rating A (best) to F (worst)is used.

A suiiicient volume of used oil is obtained from the test fordetermination of the usual used oil properties, such as pentaneinsoluble (sludge), viscosity increase, neutralization number andoptical density.

The term optical density, as used in the present disclosure, representsthe standard logarithmic ratio of intensity of an incident ray fallingon a transparent or translucent medium to the intensity of thetransmitted ray for a sample Table I Lubricant-Example N o Corrosion ofOu-Pb (in mgms,

weight loss of) Viscosity Increase (SUS) Pentane Insolubles (in mgm/lOg.

of lubricant) Sludge Rating Lacquer Rating.

Table II Lubricant-Example N o Corrosion of Cu-Pb (in mgms. weight lossof). Viscosity Increase (SUS) Pentane Insolubles (in mgm/lO g. oflubricant) Acid Number Sludge Rating Lacquer Rating The above dataclearly show that the reaction products of the invention are markedlysuperior to the blank oil as lubricants; especially as to corrosion,viscosity increase, and pentane insoluble characteristics. Examples 2, 3and 4 show results with one clay treatment at the end.

In the clay treatment, generally the amount of clay is in the range ofabout 2 to about lbs. per barrel of oil, preferably at least 5 lbs. Iftoo large an amount of clay is used, the resulting product is lessdesirable, and may even be Worse than the starting oil as to somecharacteristics.

" lubricants are obtained.

If desired, the improved lubricants of the invention may be used inblends together with other lubricants or lubricant agents, e. g., withsoap or the like in a grec se. If desired, an agent for improving theclarity of the oil may be included, e. g., lecithin, lauryl alcohol, andthe like. If desired, an agent for preventing foaming may be included,e. g., tetra-amyl silicate, an alkyl ortho-carbonate, ortho-formate orortho-acetate, or a polyalkyl silicone oil.

In view of the foregoing disclosure, variations and modifications of theinvention will be apparent to those skilled in the art, and it isintended to claim such variations and modifications broadly, except asdo not come within the scope of the appended claims.

I claim:

1. A method of processing lubricating oil stock consisting essentiallyof hydrocarbon material to yield an oil having improved inhibition tooxidation in service, which method comprises solventrefining said stock,treating the resulting solvent-refined hydrocarbon with an amount of aphosphorus sulfide in the range of about 0.1 to about 0.75% by weight ata temperature in the range of about 275 to 450 F., and then treating theresulting product with clay.

2. The method of claim 1 wherein the solventrefined hydrocarbon istreated with phosphorus pentasulfide at a temperature in the range ofabout 300 to 450 1".

3. The method of claim 1 wherein the solventrefined hydrocarbon istreated with phosphorus sesquisulfide at a temperature in the range ofabout 300 to 450 F.

4. The method of claim 2 wherein the solventrefined hydrocarbon istreated with clay prior to the treatment with the phosphoruspentasulfide, and then again subsequent to said treatment withphosphorus pentasulfide.

5. The lubricating oil obtained by the process of claim 1.

6. The lubricating oil obtained by the process of claim 2.

7. The lubricating oil obtained by the process of claim 3.

8. The lubricating oil obtained by the process of claim 4.

JOHN D. BARTLESON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,316,091 White Apr. 6, 19432,393,335 Musselman Jan. 22, 1946 2,398,429 Hughes Apr. 16, 19462,419,584 Noland Apr. 29, 1947

1. A METHOD OF PROCESSING LUBRICATING OIL STOCK CONSISTING ESSENTIALLYOF HYDROCARBON MATERIAL TO YIELD AN OIL HAVING IMPROVED INHIBITION TOOXIDATION IN SERVICE, WITHIN METHOD COMPRISES SOLVENTREFINING SAIDSTOCK, TREATING THE RESULTING SOLVENT-REFIED HYDROCARON WITH AN AMOUNTOF A PHOSPHORUS SULFIDE IN THE RANGE OF ABOUT 0.1 TO ABOUT 0.75% BYWEIGHT AT A TEMPERATURE IN THE RANGE OF ABOUT 275* TO 450* F., AND THENTREATING THE RESULTING PRODUCT WITH CLAY.